Chief Miles O'Brien is the most important man in the galaxy. This is established in continuity, thanks to Star Trek: Lower Decks' flash forward to the future. Not only is this moment absolutely hilarious in the episode, it also depicts Chief O'Brien at work, which is an ongoing, brilliantly funny internet meme.
When last the audience saw O'Brien, he was en route back to Earth as he was about to take up a post at Starfleet Academy. While What You Leave Behind did slightly side sweep the audience with this revelation, it did make sense that after years of high-pressure roles on both the Enterprise and Deep Space Nine, he would be rewarded with a slightly cushier job.
However, is there anyone who believes that Miles O'Brien would be satisfied with a relaxing role? He lives for the hustle and bustle of a constantly collapsing warp core or power grid. Grumble as he might, no one takes him seriously in this respect. Added to this, the producers of Deep Space Nine set 'O'Brien Must Suffer' into law, which suggests he may even have been fired from his role after about two weeks.
He is a character who needs to be back on a starship, keeping it from flying apart, giving her all she's got!